Most tower defence games get their title from the numerous weapon towers which players must erect to protect themselves. In the case of Steampunk Tower, the developers have gone one step further, and put a bloody great tower in the middle of the screen to act as a support structure for your weapon towers. It's a bit like Inception, only with towers.

Anyhow, this being a steampunk game, you must use a mixture of 1930s-era tech to fend off wave after wave of moisture-powered monstrosities. Infantrymen and small tanks lead the charge, but soon airships, paratroopers, and enormous steel death machines will be bearing down on your position.

The game employs several neat techniques for keeping you active throughout levels. To build defences, you tap at the base of the tower. Once built, you must position each turret upon a platform. Every time you increase your rank, the tower will gain another floor, giving you more space to plant your cannons. As your bank balance grows, you get the option to upgrade turrets by dragging them back down to the basement. You're being assaulted from both sides, so you may have to shift units from left to right depending on your turret classes and enemy vulnerabilities.

This real time interaction adds an additional layer of strategy to Steampunk Tower. You have to be quick when upgrading and switching units, as any downtime for your cannons can have fatal consequences. You can even speed up a turret's reload speed by dragging it into the tower's core - but you'd better remember to put it back on duty the moment it's completed.

It takes a fair while before things start getting challenging. We were able to ace over 50 percent of the game without a single restart. You still feel like you've earned your victories, and the desire to research and modify new weapons like the tesla keep you coming back for more. The special attacks are a blast, too, with a large red laser acting as your own personal eye of Sauron.

Steampunk Tower manages to be both accessible and nuanced, earning it a seat in the upper echelons of the tower defence conclave. It's not the toughest game out there, but it's smart and satisfying take on the tower defence formula.